polyethylene and polypropylene

8/6/2019 Polyethylene and Polypropylene

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Polyethylene and Polypropylene



D e f i n i t i o n

P o l y m e r s made fro~ monome r s h a v in g t h e b if u .n c t i o n a l g r o u p a re e t h e n ic s i n c e e t h y l e n e h a s

.r r th e s imples t a l l · h y d r o g e n a tom stru c tu re , and o th ers a re s i m p l y

) C ee C (' sub s titu tio n s o f o the r a t oms o r g roup s a t th e W, .r , y, and z p o s it io n s .

H ,'1



2 .3 . M e tho d s o f P ro d u c tio n

2 .3 .1 . H igh p re s su re (1 ,0 00 -2 ,5 0 0 a tm s .)T his w as the o riginal p r o c e s s developed by l e I in the U K using peroxide c a t a l y s t

a t lO O ·300 °C an d producing low den s ity ran dom o rien ted , low M .P . po lym er.

2 .3 .2 . In te rm e d ia te p re ssu re (3 0 ·1 00 a tm s .)

D e v e l o p e d by P hillip s P e tro le um C o . in the U SA ; u s e s M oO ) o r C r201 onalum ina as catalyst , pro du ces high d en sity p oly m er with accompany i ng in creases in

r ig id ity , c r y sta ll in i ty , tensile strength and soften ing po in t -

2 .3 .3 . L ow pressure (6-10 atms. )

T he o rigin a l p ro ce ss fo r p repa rin g high den s ity po lye thy len e w as dev elop ed b y

D r. K arl Z ie gle r in Ge rmany . It u s e s a catalyst c on sis tin g o f alum inum trietbylactivated w ith he av y m e ta l d e riv ativ es such as T iC I4• A s im ilar p ro ce ss d ev elo pe d b y

D r. G . N atta in Italy is u sed fo r the p roductio n o f polypropylene.



atm s. gage and 70 0

c . T h e e f f l u e n t goes to a s e r i e s o f flash d r u m s to r e m o v e t h e

so lv en t from the catalyst W ater is added at this po in t to d e s t r o y residual c a t a l y s t

w h ic h i s h i g h ly f l a m m a b l e i n t h e d r y c o n d i t i o n .

T h e f l a s h e d s o lv e n t i s d r i e d , r e d is t i l l e d , a n d r e c y c l e d to t h e c a t a ly s t m a k e . .u p unit.

P olye thyle ne slurry is ce ntrifuged to d ew ater, w ith th e wate r be ing tr e ated to r emov e

cataly st be fo re re cy cle . P o l y e t h y l e n e so lids are dried; extruded, and fin ished to

requ ired fo rm (pelle ts , flakes o r pow der), T he y i e l d b a s e d on e t h y l e n e is 9 5 ... 8 % .

T h e s a m e p r o c e s s , w i t h m o d i f i c a t i o n s i n r e a c t i o n c o n d it i o n s , c a n be u s e d f o r

p o l y p r o p y l e n e .



O x y g e n - -

. . . . . .-C . a m p re s so r. . . . . _ . . , _ . .

Cooler

Heoter

~epo (o ' o r

c hop~e ,,-R e o c f O . r

F lake

P o l y e t h y I . en e

Flow diagram of Imperial Chemical Industries process.



Solvent -

Recycle

MonomerCatal~st

,....--IL...--. tioRRe r +R

., . . . . . . . . . . . . . . , . .L.L. eel rc

Cyclone

Solvent

MonomerPolar

Solvent

Catalyst

FinesSolid

PolymerTo Drier

1Catafyst

Regeneratton

Typical metal oxide-catalyzed process.

Alkylate

fSolven!

Fraction-atar

Wax



Polyvinyl Chloride and Copolymers3~1~ Basic Chemistry

Addition type kinetics to produce linear polymers

(a) Polyvinyl chloride (PVC)

H H

I IC-C

I IH CI



(b) Vinyl copolymers

mCHt = = CRCl + nCR, = = CH ·X

H H H H

t - b - b - b

~ ~l ~ *where m is usually greater than n, X is a group on the comonomer such as:

carboxyl (-COOH)-vinyl ace ta te

hydroxyl (-OH)-vinyl alcoholcarboxyester(-COOR)-methyl methacrylate

nitrile (-CN)-acrylonitrile

Replacing the HX group by chlorine atoms gives the vinylidine monomer.



' . 2 . P e r t in en t P ro p e r t i e s

P V C h as a s o ft e n in g p o in t r a n g in g f r o m 8 0 ° C to 1 4 0 ° C , in c r e as in g w i th th e d eg re e

o f a f te r · c h lo r in a li o n . It d e c om p o s e s ra p id ly a t 1 4 0 °C , l ib e ra t in g Hel; c a n b e s t a b i l i z e d

a t lo w e r te m p e ra tu re s wi t h a c id n e u t r a l i z e r s s u c h a s a lk al i m e ta ) s a l ts . N o rm a l 'P V C is

a b a rd , to ug h p o l yme r , i n so lu b le in m o s t s o l v e n t s . I t c a n b e so f t e n ed b y p la s t i c iz e r s f o rm e ch an ic al w o rk in g I,

V i n y l c h lo r id e c o p o lym e rs a re fo rm u la te d to o v e rc om e s om e o f th e d is a d va n ta g es o f

P V C , p a r t ic u la r ly lo w so lv e n t so lu b il i ty a n d p o o r h ea t s ta b il i ty .



3 .3 . C o n s u m p t io n P a t t e r n

P V C w i t h o n ly sm a ll c o nc e n t r a t io n s o f p l a s t i c i z e r i s ' d e s ig n a te d a s " rig id " a n d

e x t r u d e d in h e a v y s t r u c t u r a l d e s i g n s s u c h a s p ip e a n d s h ee t s . W h en h e a v i l y p l a s t i c i z e d ,

i t c a n b e u s e d f o r m a n y e la s o m e r - t y p e p r o d u c t s .

T h e c o po ly m e r s g r e a t l y e x te n d th e u s e s f o r v i n y l p o ly m e r s , p ar t i c u la r ly w h e re

s o l v e n t s o l u b i l i t y i s d e si r a b le . T y p i c a l u s e s a r e la t e x e m u ls io n a n d s p r a y c o a t i n g s ,

e le c t r i c a l in su la tio n , t e x ti l e f a b r i c c o a t i n g s , t u b i n g , c lo th e s l in e , r a in w e a r , a n d s h ow e r

c u r t a i n s .

T h i s mUl t i p l i c i t y o f u s e s p la c e s th e v in y l p o ly m e r g ro u p s e c o nd in a n n ua l p r o d u c t l o n ,

j u s t b e h in d th e p o l y o l e f i n s .



Me tho ds o f P ro du ctio n

Em u ls io n an d su sp en s io n polymerizat ion m etho ds a re u sed com m erc ia lly ; the

la tte r is u se d on ly if high p urity p olym er is d es ire d .

In em u ls io n po lym e r iz a tio n , a typ ica l fo rm u la tio n is 1 00 p a r ts o f w ate r , 1 00 p ar tso f v i n y l mo n om e r s , 1 p a r t o f p e rsu lfa te cata lys t , an d 1 .5 p a r ts o f a d e te rge n t

em u ls ifie r . T his is fe d to a p re s su re reac to r , e ithe r co n tin uo u s o r batch, o pe ra tin g a t

5 0 °C fo r p e r io d s a s lo n g as 72 ho u rs" T he m ice llu Ja r p o lym e r p a rtic le s can be fur ther

stabil ized by addi t ion · o f m ore em uls ify in g agen t an d so ld a s v iny l la te x . If so lid

po lym er is d e s ire d , the m ix tu re is e ithe r ac id co agu la te d and d rie d o r sp ray -d rie ddi rect ly .



Water

Cata st

Deter ent

ContinuousPolymerizer

RecycleMonomer

FlashDrum

-------..._.,.~

COPQ l yme r

WetG s

AlternateRoute

Acid

Drier

Coagu la t ioo TanK

Fig. VB-4. Polymerization process for vinyl polymer.



A B S R e s in s

ABS resin (acry lo nitrile , butad ien e & styrene copo lym er), genera lly classified as an

e ngin ee rin g p la stic , is u se d in v ar io us in du strie s lik e re frige ra to r lin ers , a utomo bile c omp o ne nts ,

m o ld ed an d the rm o fo rm e d parts o f te lep ho ne , in te rco m s, m ixers, co m puter cabin ets , cam eras,

v ac uum c le an ers , m o ld ed lu gg age , toys, e tc . T he re are abo ut 109 grade s o f A BS res in s av ailable

in te rn atio nally . In In dia , the p re se nt av ailability is o n l y abou t 10 gr ades of A BS.

A m o n o m e r . .s o lu b l e p o l y b u t a d i e n e r u b b e r o r b u ta d i · .a n d a c ry lo n i t r i l e w i t h · "f t d ' . e n e c o p o ly m e r I S d is s o lv e d i n t h e s t y re n ec o n v e r s i o n S e v e r a l tr u 1 8 O I 'S a n m o d J ~ . T h i s m i x tu re i s p o l y m e r i z e d t h ro u g h p h a s e

A B S . T h ~ r a w m ! : so ~ U : t : = m ay b e u s e d ~ n t e r c h a o g e a b J y f o r h ig h i m p a c ta c r y l o n i t r i l e . o f A S S resins a r e styrene, b u ta d i e n e a n d



A B S r e s i n s e n j o y s e v e r a l a d v a n t a g e s , a s c o m p a r e d t o o t h e r s u b s t i t u t e s l i k e m e t a l s , s i n c e i ti s l i g h t i n w e i g h t , e a s y t o p r o c e s s a n d w i l l h a v e l o w e r m a i n t e n a n c e . T h e c u r r e n t d e m a n d f o r A B S

r e s i n s i s e x p e c t e d t o i n c r e a s e a s a r e s u l t o f g r o w t h i n u s e r i n d u s t r i e s t s u c h a s a u t o m o b i l e s a n d

t e l e c o m m u n i c a t i o n s .

H i g h l e v e l o f i m p o r t d u t y o n r a w m a t e r i a l s f o r A B S r e s i n h a s m a d e t h e p r i c e o f t h e p r o d u c th i g h i n t h e c o u n t r y . I f A B S w e r e t o b e a v a i l a b l e t o d a y a t t h e p r i c e o f a r o u n d R s . 4 0 p e r

k i l o g r a m , t h e p r e s e n t d e m a n d f o r t h e p r o d u c t w o u l d b e a t l e u t t w o t i m e s m o r e t h a n t h e p r e v a i l i n g

le v e l. H ig h er p la n t c a p a c i t y o f a ro u n d IS ,O O ) T PA can c o n t r i b u t e to l o w e r th e p ro du ctio n c os t

o f th e p r o d u c t .



Polycondensation Processes

Polycondensation has been defined previously as the step-wise reaction of monomers wi th

functional grouping which often eliminates small molecules such as H20. Both linear and

tridimensional polymers are made; the latter are more prevalent.

1. Phenol-FormaJdehyde

1.1. Basic Chemistry

(a) Metbylol monomer formation

OH

o + x CHaO --- ...

OH

HOHICQCH20H)

CH10H

bifunctional if x=2trifunctional if x =3

(b) Linear polymer

Substitution of non-functional group in the 4 position will block the cross-linking

possibilities shown next.



( c ) C r o s s - li n k e d t r i d im e n s io n a l p o l y m e r

n

e t c .



Pertinent Properties be repared in such a wide variety of forms, ba sed .

Phenol-formaldehyde polyme~ can ~bTf that it is impossible to give specific

on bi- and t r i f unc t i ona l group r e ac t Ion PO~SI tblles, • t' can be controlled by:. . . . f t 1 0 G neral resin c aractens ics

properties In thisboe. ou me. e. b I-produces linear soluble thermoplastics.(a) Acid solution ca t a l y s t With excess P eno

(b) Alkaline ca t a l y s t s rrect ratio of phenol to formaldehyde is reacted wi th• one-stage process-co . h ti

proper control of time and beat to yield a thermosetUng or eat reac ve

powder which can later be heated to an infusible, insoluble state via further

cross-liakiDa·• two-stage process-thermoplastic material from the acid catalysis process is

mixed with hexamethylene tetramine, a white solid which breaks down to

CH20 and NH,. The formaldehyde combines with the resin to form a

thermosetting productwith

ammonia as catalyst.Both

one- and two-stagereslns are used as commercial molding materials with the final cross-linked

polymer having good resistance to all chemicals except alkalies.

(e) A strictly linear polymer with ,000 heat fusion and solvent solubility properties

for varnishes and adhesives is made by substituting cresol (RO· CA ·CH3) for

phenol with the methyl group blocking the trifunctional position.



Me tho ds o f P ro du ctio n

Po lym eriza tio n is an exo the rm ic re ac tio n w hich m ust be cont ro l l ed . by batch.

reac tio n a s the m a te r ia l rap id ly chan ge s v isco sity .

Pheno l , fo rma ldehyde , a nd ca ta ly st a re m ix e d to ge the r in a ja ck e te d au toc l ave

(re s in k e ttle ) an d he a te d with s te am . A fte r re a c tio n s ta r ts , the he a t o f re a c tio n is

r emov e d by re tlux ing and w ate r co o lin g. In the early s tage s o f re ac tio n , the heav ie r

v is c o u s re s in separa tes a s a bo ttom l ayer with an aq ueou s la y e r a t th e t op .

Dehydra t ion is n e x t comple t ed in the k e ttle by a com bin a tio n o f he a t a n d v a cu um ..

T he fu sed re s in a t 130 -150 °C is rem ov ed from the ke ttle , coo led and groun d to a fin e

powde r .

T he heat reac tiv e m old in g pow de r p repa red abo v e can be mixe d with fi l lers,

co l o r i n g agent , l ub r i c an t s , an d ca ta ly s t in a r ibbo n ble nd er o r ba ll m ill . It is then

hea ted fu rthe r o n a pa ir o f d iffe ren tia l he a tin g ro lls to p rep are fa s t cu rin g com m e rc ia l

p he no lic m o ld in g p ow d er.



Batch Resin Kettle

Resins inH20 So .

---Hexamethylene

tetramioe, Lubricant

Adhesiyes &

Coatia

Fig. VB·5. Phenol-formaldehyde resin products production.

Ihermosetti"RMatting PONder



Epoxy Polymers•

-

(a) Epoxidation is the addition of an oxygen atom across a C = = C to give

The oxygen transfer agent can be peracids such as peracetic acid

(CH3 •CO • 0 • 0 • CO • CH3), hydrogen peroxide, or chlorhydrin (HOCl) foUowedby He} removal. The latter gives epichlorhydrin.

CH2=CH-CH3 +el2 CH2=CHCH2Cl

1aU y1chloride

H O C I(-He1 CHz -Cl CHOHCH2 Cl

epichlorhydrin



( b ) E p o x i d e p o l y m e r s c o n t a i n a n e p o x y g r o u p a t t h e e n d s o f t h e p o l y m e r . F o r

e x a m p le , t h e r e a c t i o n o f e p i c h l o r h y d r in w it h b i s p h e n o l - A ( p r e p a r e d b y

c o n d e n s a t io n o f a c e to n e w i th p h en o l ) i s a c o n d e n s a t io n W ith lo s s o f Hel :o

oQC H 30/\ -He!

H -c- O H f C H 2 - CH -CH sC J m ..

C H 3

o

C H 3

'0 .- . -O-CHCHOH -CH 2

C H3

n

E p ic h lo rh y d ri n s a r e a l s o c o n d e n s e d w i t h o t h e r h y d r o x y l g r o u p s in c o m p o u n d s

s u c h a s r e so rc in o l , h y d r o q u i n o n e , e th y le n e g ly co l, a n d g ly ce r o l.



( c ) E p o x y m o n o m e r s c a n b e o b ta in e d f r o m u n s a tu r a te d n a tu r a l p ro d u c ts s u c h a s

v e g e t a b le o i l s , p a rt ic u la rly s oy b ea n o i l , a n d t a l l o i l f r o m w o o d p u lp i n g . T h e

m o le c u la r s t r u c tu r e o f p o l ym e r s f r om e p o x i d i z e d n a tu r a l p ro d u c t m o n o m e r s i se x t r e m e ly c om p le x . B o t h l in ea r a n d c r o ss - lin ke d p o ly m e r s a r e p o s s ib le ,

( d ) S y n th e t i c e p o x y m o n o m e r s a r e o b ta in e d v ia b u ta d ie n e c y c l i z a t io n a a d

p e r o x i d a t i o n

eH = C H 2

.( v in y lc y ck Jh e uD C )

o

1\O-CH-CH



Me tho ds o f P ro duc tio n

Epo xy po lym e rs a re m a n ufa ctu re d largely by batch p ro ce ss in g be ca use o f low

to nn age , m u ltip le fo rm u la tio n m arke tin g. In cre ased dem an d o f se ve ra l epoxy re sin s has

le d to the dev e lopm en t o f co n tin uo us p ro ce ss ing, u s in g tw o o r m ore m ix in g reac to rs in

s e r i e s .

Epoxy po lym er p ro ce sse s a re re la tiv e ly sim p le an d use the so lv e n t polymer izat ion

m ethod . U nsa tu ra te s , epo x id iz ing agen t, an d so lv en t a re co n tac te d o n a p ro gram m ed

a dd itio n sche du le fo r giv en tim e -te m pe ra tu re co nd itio ns . W ate r o r other condens ib les an dso lvents are rem ov ed and the so lid o r o il re sin fraction is giv en a f inal p urific atio n a nd

drying .

U n usua l en gin e erin g des ign fea tu re s a re :

• Sa fe ty p re cau tio n s in hand lin g the pe rox id iz in g c ompound s to av oid detonat ing

cond i t ions• Exac t tem pera tu re con tro l w i t h p ro v is io n s fo r rap id dump i ng an d w a te r flu shin g

fo r a run aw ay reactio n

polyethylene and polypropylene

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